Methods and apparatus for crossing vascular occlusions

ABSTRACT

Methods and apparatus for crossing totally to substantially occluded blood vessels by passing a redirectable wire such as a guidewire from a relatively proximal point past the occlusion within a subintimal space formed between the intimal layer and the adventitial layer of a blood vessel wall. The wire may be advanced to a point distal to the occlusion, and thereafter deflected back into the blood vessel lumen, typically using a deflecting catheter which is advanced over the guidewire after it has been positioned within the subintimal space. The deflecting catheter may include a flapper valve assembly or preformed actuator wire for redirecting the guidewire. After the guidewire is returned to the blood vessel lumen, the deflecting catheter may be withdrawn, and the guidewire may be available for introduction of other interventional and diagnostic catheters for performing procedures such as stenting.

FIELD OF THE INVENTION

1. The present invention relates generally to medical devices, kits, andmethods used in the treatment of vascular occlusions. More particularly,the invention relates to systems and procedures for crossing chronicocclusions in blood vessels with guidewires that may facilitateperformance of subsequent treatment and therapies including angioplasty,atherectomy and stenting procedures.

BACKGROUND OF THE INVENTION

2. Cardiovascular disease is a leading cause of mortality worldwide thatcan take on many different forms. A particularly troublesome form ofcardiovascular disease results when a blood vessel becomes totallyoccluded with atheroma or plaque, referred to as a chronic totalocclusion. Until recently, chronic total occlusions have usually beentreated by performing a bypass procedure where an autologous orsynthetic blood vessel is anastomotically attached to locations on theblood vessel upstream and downstream of the occlusion. While highlyeffective, such bypass procedures are quite traumatic to the patient.Recently, catheter-based intravascular procedures have been utilized totreat chronic total occlusions with increasing success. Catheter-basedintravascular procedures include angioplasty, atherectomy, stenting, andthe like, and are often preferred because they are much less traumaticto the patient. Before such catheter-based treatments can be performed,however, it is usually necessary to cross the occlusion with a guidewireto provide access for the interventional catheter. In some instances,crossing the occlusion with a guidewire can be accomplished simply bypushing the guidewire through the occlusion. The guidewire remains inthe blood vessel lumen and provides the desired access path. In manycases, however, the guidewire inadvertently penetrates into thesubintimal space between the intimal layer and the adventitial layer ofthe blood vessel as it attempts to cross the occlusion. Once in thesubintimal space, it is very difficult and impossible in many instancesto direct the guidewire back into the blood vessel lumen. In such cases,it will usually be impossible to perform the catheter-based interventionand other procedures may have to be employed that are relatively moretraumatic. Catheters and methods for forming lateral penetrationsthrough tissue to and from blood vessels past total occlusions aredescribed in U.S. Pat. Nos. 5,443,497; 5,429,144; 5,409,019; 5,287,861;WO 97/13463; and WO 97/13471. Catheters having side guidewire entryports spaced proximally from their distal tips are also described inU.S. Pat. Nos. 5,464,395; 5,413,581; 5,190,528; 5,183,470; 4,947,864;and 4,405,314. These and a variety of other specific interventional andpharmaceutical treatments have been devised over the years with varyinglevels of success for different applications.

SUMMARY OF THE INVENTION

3. The present invention provides methods and apparatus for crossingsubstantial or total occlusions in blood vessels. It is an object of theinvention to traverse vascular occlusions or other blockages formedwithin blood vessels in order to provide pathways for the placement ofguidewires or other interventional devices as part of an overall effortto restore or provide adequate circulation. It is advantageous to crossa substantially occluded blood vessel by finding and/or creating a pathwith the least or relatively low resistance through or around at least aportion of the occlusion which may include travel along or between thelayers of a blood vessel wall in regions such as the subintimal space.The invention further provides methods, kits, and apparatus whichfacilitate crossing a chronic total occlusion in a blood vessel with aguidewire. In particular, catheters, guides, or other apparatus providedherein may be used with conventional or specialized guidewires to director redirect the guidewires from a subintimal space, or other areasbetween the different layers of a blood vessel wall, back into the bloodvessel lumen. The disclosed apparatus include devices formed withrelatively simple construction, and may be used in a relativelystraight-forward manner.

4. One aspect of the invention provides apparatus for crossing avascular occlusion by directing a lead device such as a guidewire aroundat a least a portion of the obstruction within the blood vessel wall. Adeflecting catheter may controllably deflect or direct the guidewirethrough or around a vascular occlusion formed within the natural lumenof the vessel, and may direct the guidewire within a region in betweenthe various layers of the vessel wall to completely or partiallycircumvent the blockage. The deflecting catheter may provide anycombination of these controllable movements to position the guidewire ina manner that can facilitate interventional treatments such as stenting.Another variation of the invention includes a guidewire deflectionsystem comprising a catheter body formed with at least one lumenextending along its length, a nosecone formed at the distal end of thecatheter body having a distal and a lateral opening. The regionsurrounding the lateral opening may include an adjacent inclinedsurface. The distal opening and the lateral opening are both incommunication with the catheter body lumen. In addition, a cannula maybe included having a cannula port in communication with at least onepassageway extending through at least a distal portion of the cannula.The distal end of the cannula may be configured to communicate with theinclined surface adjacent to the lateral opening to deflect the cannulaaway from the longitudinal axis of the catheter body. The distal portionof the cannula may further have a pre-formed shape resilient curve, andmay be slidably positioned within the lumen of the catheter body. Thedistal portion may have a relatively axially aligned configuration withthe lumen when the cannula is positioned within the catheter body, and arelatively curved configuration with the lumen when the cannula travelsalong the inclined surface and through the lateral opening of thecatheter body when the cannula is distally advanced through the lumenwithin the catheter body. The guidewire deflection system may furthercomprise a guidewire configured to pass through the passageway of thecannula. A variety of imaging components or markers may be alsopositioned on various portions of the wire, cannula or catheter body. Ahub assembly rotationally secured to the proximal end of the catheterbody may be selected to controllably rotate the cannula and the catheterbody.

5. In yet another embodiment of the invention, an intravascular catheteris provided having a catheter shaft formed with at least onelongitudinal lumen. A nosecone may be positioned at the distal end ofthe catheter shaft having a first port in communication with thelongitudinal lumen formed with a first cross-sectional area, and asecond port in communication with the longitudinal lumen formed with asecond cross-sectional area, wherein the first cross-sectional area isrelatively larger that the second cross-sectional area. A cannula may beslidably positioned within at least a portion of the longitudinal lumenof the catheter shaft, and may be configured for passage through thefirst port which is relatively larger, but not through the second portof the nosecone which is relatively smaller in size. A guidewire may bealso slidably positioned within at least a portion of the cannulapassageway, and may be configured for passage through an inclinedsurface formed adjacent to the second port. The nosecone may furtherinclude imaging components or radiopaque markers that providesdirectional orientation.

6. Another embodiment of the invention provides a redirectableintravascular guidewire catheter. The catheter may be formed with acatheter shaft and a guidewire deflector formed at the distal end of thecatheter shaft. The guidewire deflector may be formed as a noseconeassembly having a distal end port, a lateral port, and a relativelyinternal or external flapper assembly with a deflectable extension. Thedeflectable extension of the flapper assembly may have a first positionthat directs a guidewire tip through the distal end port when theguidewire tip is positioned relatively distal to the deflectableextension. It may further have a second position that directs theguidewire tip through the lateral port when the tip is positionedrelatively proximal to the deflectable extension and advanced thereafterin a relatively distal direction. Additionally, a guidewire may beincluded in the catheter that is slidably positioned within the lumen ofthe catheter shaft. A portion of the flapper assembly may be also formedof a fluoroscopic material to provide an orientation marker fordirectional placement of a guidewire.

7. A redirectable guidewire catheter is further provided in accordancewith the concepts of the invention comprising a catheter shaft, anactuator wire, and guidewire. The catheter shaft may be formed with afirst lumen and a second lumen each extending along the catheter shaftrespectively to a first distal opening and a second distal opening. Theactuator wire may be slidably positioned with the first lumen of thecatheter shaft, wherein the actuator wire is formed with a preformeddistal end to provide an actuated position that is biased towards thesecond distal opening when advanced relatively distal through the firstdistal opening. Furthermore, the actuator wire may extend only within orbeyond the outer surface of the catheter shaft at a relatively distal ordistal most end portion of the catheter shaft. The guidewire may beslidably positioned within the second lumen of the catheter shaft, andmay be deflected when advanced relatively distal through the seconddistal opening when the actuator wire is placed in its actuatedposition. In another variation of the invention, the redirectableguidewire catheter may have a catheter shaft with a first lumen and asecond lumen each extending along the catheter shaft. A nosecone may beformed at the distal portion of the catheter shaft, wherein the noseconeincludes a distal orifice and an interior region formed with a taperedsurface. The actuator wire may be formed with a distal tip that isslidably positioned with the first lumen of the catheter shaft, whereinthe distal tip of the actuator wire is redirected substantially awayfrom the longitudinal axis of the catheter shaft when advancedrelatively distal along the tapered surface of the nosecone and throughthe nosecone orifice. The guidewire may be slidably positioned withinthe second lumen of the catheter shaft, and may be deflected away fromthe longitudinal axis of the catheter shaft by contacting the redirectedactuator wire when the guidewire is advanced relatively distal throughthe distal orifice.

8. Yet another variation of the invention provides an intravascularcatheter for selectively deflecting a guidewire that includes a catheterbody formed with a distal end and a longitudinal lumen formed along atleast a portion of the catheter body. A support tube may be formed witha distal tube end that includes a cut-out portion to accept the distalportion of a cannula. The support tube may be slidably and rotatablypositioned within the longitudinal lumen of the catheter body. Thecannula may include at least one passageway extending through at least adistal end portion of the cannula, wherein the distal portion of thecannula has a pre-formed shape resilient curve that may communicate withthe cut-out portion when the cannula is slidably positioned within theconduit of the support tube. The proximal tube end of the support tubemay be connected to a rotating assembly to rotate the support tuberelative to the catheter body. Another variation of the intravascularcatheter may include a support tube connected to the distal cannula end,wherein the support tube is formed with a distal tube end section, aproximal tube end section, and a backbone connecting the distal and theproximal tube end sections. The support tube or the distal cannula endmay be preformed with a predetermined shape to deflect the distalcannula end away from the longitudinal axis of the catheter body whenthe distal cannula end is extended proximally past the distal end of thecatheter body.

9. Another aspect of the invention provides methods for crossing asubstantially occluded blood vessel. The method may include the steps ofselecting a guidewire with a deflectable distal tip configured forplacement in a blood vessel wall, creating a longitudinal dissectionplane within the blood vessel wall by inserting the guidewire into bloodvessel wall from within the blood vessel lumen at a proximal locationrelative to a vascular occlusion, forming a channel along the bloodvessel wall by advancing the guidewire in a relatively distal directionalong the blood vessel wall, and selectively deflecting the distal tipof the guidewire at a relatively distal location relative to theproximal location back into the blood vessel lumen. An interventional ordiagnostic catheter may be advanced over the deflected guidewire from aposition relatively proximal to the occlusion, through the channel, andback into the blood vessel lumen.

10. Other variations of the invention described herein also includemethods where total occlusions are crossed by first forming a track orchannel from a lumen in a blood vessel into a subintimal space betweenan intimal layer and an adventitial layer of the blood vessel. The trackmay be formed so that it extends from a location proximal of the totalocclusion to a location which is relatively distal to the totalocclusion, or at any positioned located therebetween. A passage may bethen formed from the track back into the blood vessel lumen at therelatively distal location. In one variation of the invention, the trackmay be formed by advancing a wire through the blood vessel lumen intothe subintimal space by typically advancing the wire until it encountersthe total occlusion. By continuing to advance the wire in a generallydistal direction, it may pass into the subintimal space of the bloodvessel, and may be further advanced toward a desired distal location.After the wire is located or confirmed at a point relatively distal tothe total occlusion or original point of insertion, it may be typicallydeflected from the track or channel back into the blood vessel lumen.

11. In some exemplary methods described herein, the wire may bedeflected using a deflecting catheter. Typically, the deflectingcatheter may be advanced over a proximal end of the wire and advancedinto the track within the subintimal space. The wire and the deflectingcatheter may be manipulated so that the wire is deflected laterallythrough the intimal layer back into the blood vessel lumen. Suchdeflecting catheters may be also useful in axially supporting the wireas it is advanced into and/or through the track, i.e. the catheter canenhance the “pushability” of the wire when it is advanced forwardthrough any resisting material. Specific designs for such deflectingcatheters are described in detail below. The wire, which is initiallypositioned within the track in the subintimal space, may bealternatively withdrawn through the deflecting catheter and exchangedfor a second wire or device suitable for penetrating through the intimallayer of the blood vessel wall back into the lumen. It will beappreciated that the wires and/or deflecting and other catheters may befreely exchanged over or through one another in a conventional matterwithout departing from the scope of the invention.

12. Various imaging techniques may be used in accordance with theinvention to determine where the wire and/or deflecting catheter arepositioned with respect to a vascular occlusion so that the wire may bereturned to the blood vessel lumen at a desired location or beyond theocclusion. For example, the position determination can be made byfluoroscopically imaging the blood vessel in a conventional manner.Alternatively or additionally to such fluoroscopic imaging,intravascular imaging, e.g. intravascular ultrasonic imaging (IVUS), anda variety of optical imaging modelities, such as optical coherencetomography (OCT), may be employed. For example, an ultrasonic imagingguidewire may be used to initially access the subintimal space and/ormay be exchanged for the wire which is used to access the subintimalspace. An imaging guidewire present in the subintimal space may readilydetect the presence or absence of occluding material within the bloodvessel lumen. The transition from detecting occluding material to thelack of the same is a strong indication that the position of theguidewire has advanced beyond the total occlusion. The wire may bedeflected thereafter and returned towards the blood vessel lumen. Aftera passageway is formed from the track or channel back into the bloodvessel lumen, and a wire is in place across the total occlusion, thewire may be used as a guidewire for positioning interventional anddiagnostic catheters across the obstruction. Interventional cathetersare often positioned across the total occlusion for treating theocclusion, and include devices such as angioplasty balloon catheters,rotational atherectomy catheters, directional atherectomy catheters, andstent-placement catheters.

13. Another aspect of the invention provides methods for crossing avascular occlusion with a deflecting wire. The wire deflecting step mayinclude deflecting a cannula from the subintimal space of a blood vesselwall back into the blood vessel lumen, and thereafter passing the wirethrough a path defined by the cannula, typically by a lumen within thecannula. The cannula may be advanced over the wire after the wire isdisposed or advanced within the subintimal space, and acannula-deflecting step may be also included that involves distallyadvancing a resilient or preformed curved end portion of the cannulafrom a constraining lumen formed within a surrounding catheter or sheathback into the blood vessel lumen. Alternatively, a wire-deflecting stepmay comprise advancing a deflecting catheter over the wire which hasbeen advanced into the subintimal space. A cannula may then be advancedthrough a lateral opening of the deflecting catheter, and penetratethrough the intimal layer to define a path for the wire back into theblood vessel lumen. A wide variety of steerable and actively deployedcannulas may also be used in the foregoing applications.

14. The present invention further provides kits for crossing vascularocclusions comprising a wire-deflecting catheter having a lumen ormechanism capable of laterally deflecting a wire. The kit may furthercomprise instructions setting forth any of the methods described above.Other methods and apparatus formed in accordance with the invention, asspecifically described herein, may be also combined to provide numerouskits for many applications as in the treatment of coronary artery andperipheral vascular occlusions. Optionally, the kits provided herein mayfurther comprise a wire for penetrating into the subintimal space and/orback into the blood vessel lumen. The kit may still further comprise apackage for containing a wire deflecting catheter, instructions for itsuse as described in the various methods herein described, and otheroptional devices including additional wire(s). Suitable packages includepouches, trays, tubes, boxes, and the like. The instructions may beprinted on a separate package insert or may be printed in part or inwhole on the packaging itself. The components of the kit within thepackage may be sterilized by conventional procedures.

15. Apparatus according to another aspect of the invention provideswire-deflection systems. Exemplary wire-deflection systems usuallycomprise a wire-deflecting catheter which includes a catheter body and adeflecting cannula. The catheter body has a proximal end, a distal end,and at least one lumen extending through at least a distal portionthereof. The lumen also has a distal opening and a lateral opening. Inaddition, the cannula has a proximal end, a distal end, and at least onelumen extending through a distal portion thereof. The distal portion ofthe cannula may also have a preformed, resilient curve. The cannula isslidably disposed within the lumen of the catheter body to assume (a) astraightened configuration when the cannula is proximally retractedwithin the catheter body lumen and (b) a curved configuration when thecannula is extended laterally through the lateral opening of thecatheter body. In this way, the cannula can be selectively deflectedthrough the intimal layer of the blood vessel back into the lumen of theblood vessel according to some of the preferable methods describedherein. The system may further comprise a wire configured to passthrough the cannula lumen. The wire may be a conventional guidewire or amodified wire having a sharpened distal tip intended particularly forpenetrating the intimal layer of the blood vessel wall. Optionally, thewire may further comprise an imaging apparatus such as an ultrasonicimaging means. The catheter body may include a fluoroscopically visiblemarker near its distal end. The marker can be configured to permitvisual determination of the rotational orientation of the distal end ofthe catheter body when viewed as a two-dimensional fluoroscopic image.The catheter body will usually be reinforced to enhance torsionalrigidity, and may further comprise a distal nose cone wherein the distaland lateral openings are defined within the nose cone. The distal end ofthe cannula will usually be pre-formed in a smooth curve which mayextend over an arc in the range from about 15 to 135 degrees, usuallyfrom about 45 to 90 degrees. The preformed curve may also have a radiusin the range from approximately 0.5 mm to 15 mm, usually fromapproximately 2 mm to 10 mm. These and other objects and advantages ofthe invention will become more apparent upon further consideration ofthe entire specification and drawings. Additional aspects and details ofthe invention will become more apparent to those skilled in the relevantare upon review of the following detailed description of the inventionset forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

16.FIG. 1 is a schematic illustration of a coronary artery showing theintimal layer, the medial layer, and the adventitial layer.

17.FIG. 2 is a schematic illustrations of a total occlusion within thecoronary artery of FIG. 1, shown in full section.

18.FIGS. 3A-3D illustrate the method of the present invention forcrossing a total occlusion with a wire using a deflecting catheter.

19.FIG. 3BB illustrates an alternate guidewire advancement step for themethod of FIGS. 3A-3D.

20.FIG. 4 illustrates the distal end of a deflecting catheter formed inaccordance with the invention.

21.FIG. 5 illustrates the distal end of another deflecting catheteruseful in the methods of the present invention.

22.FIG. 6 illustrates the distal end of another embodiment of theinvention that provides a deflecting catheter.

23.FIG. 7 illustrates a wire-deflecting catheter system formed inaccordance with the present invention.

24.FIGS. 8-9 are cross-sectional views of the distal end of a cathetersimilarly shown FIG. 7, illustrating an internal cannula in a retractedand advanced configuration, respectively.

25.FIG. 10 is a schematic illustration of a proximal hub of a catheterfor deflecting and directing a guidewire in accordance with the methodsand apparatus of the invention.

26.FIGS. 11A-11B illustrate variations for rotationally keying theproximal end of catheter shafts.

27.FIG. 12 illustrates variations for rotationally keying the distal endof a catheter.

28.FIGS. 13A-C provide illustrations of a nosecone for a guidewiredeflection catheter system formed in accordance with the invention.

29.FIGS. 14A-B are cross-sectional side views of a nosecone connected tothe distal end of a catheter shaft with an internally positioned cannulaand guidewire.

30.FIGS. 15A-E are simplified side views of a flapper mechanismpositioned at the distal portion of a catheter that controllablydeflects a guidewire through a distal end port and/or a lateral port.

31.FIGS. 16A-B are simplified side views of external guidewiredeflecting mechanisms that are positioned relatively outer to thecatheter shaft body.

32.FIGS. 17A-E illustrate a redirectable guidewire catheter having apreformed actuator wire that deflects a slidable guidewire positionedwithin an adjacent lumen.

33.FIGS. 18A-C show the distal section of a nosecone formed with asingle orifice that may be positioned at the distal end of aredirectable guidewire catheter.

34.FIG. 19 is a simplified perspective illustration of the distalportion of an intravascular catheter that includes a support tube formedwith a distal end portion for directing a preformed cannula.

35.FIG. 20 is a simplified perspective illustration of the distalportion of an intravascular catheter that includes a support tube havinga backbone for supporting the deflective movement of an internallypositioned cannula.

DETAILED DESCRIPTION OF THE INVENTION

36. The present invention provides methods and apparatus for crossing asubstantially or totally occluded blood vessel. Each of the disclosedembodiments may be considered individually or in combination with othervariations and aspects of the invention. The methods and apparatusprovided herein may be useful in coronary arteries and other bloodvessels with or without assistance from imaging techniques from variousregions within the body including areas within or adjacent to bloodvessel walls. While the some aspects of the invention may beparticularly applicable for the treatment of coronary artery disease,they are also useful and equally applicable in the treatment of otherarteries and veins, and for other conditions including peripheralvascular diseases.

37. As shown in FIG. 1, for example, a relatively normal non-diseasedartery (A) generally comprises an arterial wall formed with a number ofdistinct layers. An innermost layer may be referred to herein as theintimal layer (I) which includes the endothelium, the subendotheliallayer, and the internal elastic lamina. A medial layer (M) of the bloodvessel is located concentrically outward from the intimal layer (I), andwithin another layer known as the adventitial layer (AL) which may beconsidered the relatively outermost layer. Beyond the adventitial layer(AL) generally lies surrounding extravascular tissue. As usedhereinafter, the region between the intimal layer (I) and theadventitial layer (AL), generally including the medial layer (M), willbe referred to as the subintimal space. It is generally the subintimalspace through which the wires, deflecting catheters, and other cathetersof the invention, will pass at least in part when crossing a total ofsubstantially occluded blood vessel. The guidewires and deflectingcatheters described herein may be formed of appropriate dimensions forplacement and travel within these regions of the blood vessel wall. Formost applications described herein, it is most often preferable totravel within the layers of the blood vessel wall, and across the innerwall of the blood vessel into the vascular lumen, without penetratingthe outer wall region which would present additional safety concerns toa patient. These methods and apparatus may be of course directed to anyregion formed between other layers of a blood vessel wall other thanthose particularly described above.

38.FIG. 2 provides an illustration of a total occlusion (TO) within anartery (A) such as a coronary artery. The total occlusion (TO) maycomprise atheroma, plaque, thrombus, and/or other occluding materialsnormally associated with cardiovascular disease. A “total” occlusion maybe described to include an obstruction consisting of occluding materialthat substantially blocks or occludes the entire lumen (L) of the artery(A), or any other blood vessel, so that blood flow through the vessel issubstantially stopped or hindered. The invention may be particularlyapplicable for patients with a totally occluded artery that is notimmediately life threatening since the tissue distal to the occlusionmay receive oxygenated blood from collateral arteries and circulation.However, the blood supply is usually insufficient, and it is oftendesirable to treat the occlusion by an intravascular intervention, suchas angioplasty, atherectomy, stenting, or the like, to restore bloodflow through the affected vessel. Before most of these and otherinterventional procedures can be performed, a guidewire is generallyplaced across the occlusion. When a vascular occlusion prevents theplacement of a guidewire across the obstruction, one aspect of theinvention thus provides various methods for crossing the substantiallyor totally occluded blood vessel. A guidewire may be initially selectedwith a deflectable distal tip configured for placement within or inbetween the layers of a blood vessel wall. A longitudinal dissectionplane may be created within the blood vessel wall by inserting theguidewire into blood vessel wall from within the blood vessel lumen at aproximal location relative to a vascular occlusion. A channel may beformed in between the layers of and along the blood vessel wall byadvancing the guidewire in a relatively distal direction along the bloodvessel wall. Various imaging procedures may be performed to identify therelative location of the occlusion and blood vessel lumen. For example,imaging of a coronary may be accomplished from a position in a veinadjacent to the coronary artery. When the relative positioning of theguidewire and the occlusion are verified, the distal tip of theguidewire may be selectively deflected at a relatively distal locationrelative to the proximal location back into the blood vessel lumen. Uponplacement of a guidewire across the vascular occlusion, interventionalor diagnostic procedures may be subsequently performed over theguidewire, and more specifically, the interventional or diagnosticcatheter may be advanced over the deflected guidewire from a positionrelatively proximal to the occlusion, through the channel, and back intothe blood vessel lumen. The distal tip of the guidewire may be alsodeflected by providing the guidewire tip with a resilient curved end,and distally advancing the guidewire from a constraining lumen into theblood vessel lumen.

39. Another aspect of the present invention provides methods of crossinga vascular occlusion by controllably directing a deflectable wire intoand through a blood vessel wall as described in FIGS. 3A-D. For purposesof illustration, this series of figures may represent an upper portionof an occluded artery (A) as shown in FIG. 2. A wire 10 may be advancedthrough the lumen (L) of an artery (A), as shown in FIG. 3A, until itencounters a total occlusion (TO). At that time, it may be possible forthe wire 10 to be distally advanced through the occlusion withoutdeflecting into the blood vessel wall. Should that occur, subsequentrepositioning or redirecting of the guidewire according to the methodsof the present invention may be performed, but may not be necessary.More usually, however, the wire 10 is not able to traverse a substantialocclusion by distally advancing the wire through the obstruction. Thewire 10 may likely advance into the subintimal space within the mediallayer (M) as shown in FIG. 3A. Of course, the wire 10 may also travelinto or around at least a portion of the total occlusion (TO) before orwhile it is distally advanced. The intimal layer (I) and the adventitiallayer (AL) together may define a tissue plane through which the wire 10will naturally pass as the wire is pushed distally from its proximalend. The wire 10 may continue to advance further until its tip passesbeyond the distal end of the total occlusion (TO) as shown in FIG. 3B.The tip could axially or distally advance well beyond the totalocclusion to a desired location or until advancement is ceased. Althoughthe guidewire 10 in FIG. 3B is shown as being advanced without support,in some instances the guidewire may however encounter significantresistance as it enters and/or passes through the space between theintimal layer (I) and the adventitial layer (AL), or any other layerswithin a blood vessel wall. When resistance is encountered, thedeflection catheter 20 may be used to axially support and enhance the“pushability” of the guidewire 10 by advancing the catheter over theproximal end of the guidewire to a location just proximal of the distaltip of the guidewire as shown in FIG. 31BB. The guidewire 10 andcatheter 20 may then be advanced together or sequentially, e.g.advancing the guidewire a short distance followed by advancing thecatheter, as needed to direct the distal tip of the guidewire, or alateral port 22 formed in the catheter, to a relatively distal locationwhich may be proximal to or past the total occlusion (TO).

40. When the distal tip of the guidewire 10 is advanced to a desiredlocation without additional support from the deflecting catheter 20, andis positioned beyond the total occlusion (TO), the deflecting cathetermay be advanced over the wire 10 by coaxial introduction over theproximal end of the wire until it approaches the total occlusion asshown in FIG. 3B. The deflecting catheter 20 may be further advancedover the wire 10 until its distal tip also extends beyond the totalocclusion (TO) as illustrated in FIG. 3C. The deflecting catheter 20includes a redirecting mechanism for laterally deflecting the wire 10 sothat it may pass back in a radially inward direction through the intimallayer (I) back into the blood vessel lumen (L) when the catheter issequentially moved in a relatively distal direction, and a relativelyproximal direction thereafter. Rather than advancing and withdrawing thecatheter 20 in a proximal direction, the guidewire 10 may be withdrawnand advanced in a distal direction to be deflected. The deflectionmechanism may be selected from various redirecting devices an may take avariety of forms as described below. For example, as shown in FIG. 3C, alateral port 22 is provided in the deflecting catheter 20. The wire 10may be retracted so that its distal tip lies proximally of the lateralport 22, and may then be advanced distally so that the wire passeslaterally outwardly through the port and back into the blood vessellumen as shown in FIG. 3D. Various deflecting catheters and apparatusdescribed herein for directing and redirecting a guidewire within ablood vessel wall may be selected to perform these procedures inaccordance with the concepts of the invention.

41. The location and orientation of the deflecting catheter and wireassembly may be monitored in various ways to carry out the describedmethods for crossing a substantially occluded blood vessel. Inparticular, it may be desirable to assure that the distal tip of thewire 10 and the port 22 or other deflecting mechanism of the deflectingcatheter 20 is properly positioned beyond the total occlusion (TO)without being advanced excessively beyond the end of the totalocclusion. Typically, it may be desirable to position the deflectingmechanism at a range from approximately 0 to 2 cm beyond the distal endof the total occlusion (TO), and preferably from 0 to 0.5 cm. Asdiscussed above, the positioning of the relative components may in someinstances be performed using conventional fluoroscopic imaging. Forexample, it may be sufficient to provide suitable radiopaque markers onthe wire and/or on the deflecting mechanism of the deflecting catheter20 to permit visual positioning and rotational orientation of the tipvia fluoroscopy. Often, however, it may be desirable to provideultrasonic or other imaging at or near the total occlusion. A wire 10may be thus provided with ultrasonic imaging so that the presence andthe absence of the occluding material may be detected as the wire isadvanced passed the total occlusion (TO). Alternatively, the deflectingcatheter 20 may be provided with ultrasonic imaging in the form of aphased array located near the distal tip (not shown). Ultrasonic imagingguidewires are known to those skilled in the relevant field and aredescribed in the patent literature as in U.S. Pat. No. 5,095,911, thefull disclosure of which is incorporated herein by reference. In yetanother alternative, an imaging guidewire may be advanced to the regionof the total occlusion (TO) in a direction opposite to that of the wire10 and catheter 20. In this way, the imaging guidewire need not advancethrough the total occlusion, but could still detect advancement of thecatheter and/or guidewire, particularly if ultrasonically opaquecomponents were provided on either or both of the catheter and wire. Inyet another alternative, an ultrasonic imaging catheter or guidewirecould be positioned in a vein adjacent to the arterial occlusion site,allowing imaging of the entire occluded region while the guidewire isadvanced there through. Other imaging modalities may be employedincluding apparatus such as optical coherence tomography (OCT) (see U.S.Pat. Nos. 5,321,501; 5,459,570; 5,383,467; and 5,439,000), fluorescenceimaging (see U.S. Pat. Nos. 4,718,417; and 5,106,387), and Ramanspectroscopy (WO 92/18008).

42. Another desirable feature of the methods prescribed by the presentinvention includes the rotational positioning of the deflecting catheter20. It will be appreciated that the direction of deflection is usuallyselective, and it will be therefore desirable to aim the deflectingmechanism from the subintimal space back toward the arterial or bloodvessel lumen (L). If the catheter 22 is provided with ultrasonicimaging, such imaging can be used for rotationally positioning thedistal tip of the catheter. The catheter may be rotationally rigid sothat rotation of its proximal end may position the distal end of thedevice in a substantially similar manner or orientation. By detectingthe presence or relative location of the blood vessel lumen (L), thedeflecting port 22 or other deflecting mechanism can be properlypositioned. In an alternative embodiment, as further illustrated below,a catheter may include a rotationally specific fluoroscopic marker,preferably towards its distal end region. The marker may be such that byobserving the two-dimensional image of the marker by fluoroscopicimaging, the rotational direction of the catheter tip can be determined.

43.FIGS. 4-6 illustrate several exemplary deflecting mechanisms for thecatheters provided by the present invention. As shown in FIG. 4, thedistal end of a catheter 30 may have a distal port 32, a lateral port34, and a passive deflecting mechanism 36. The passive deflectingmechanism may include a first and a second inclined guiding surface 31and 33. The first inclined guiding surface 31 may be formed in arelatively distal position, and may be formed to direct the proximal endof a guidewire (not shown) into the main lumen of the catheter from thedistal port 32. The guidewire may be thereafter displaced relativelyproximal to the catheter so that the distal end of the guidewireapproaches and passes the passive deflecting mechanism 36 in arelatively proximal direction. The second inclined guiding surface 33,which may be formed in a relatively proximal position, may thereafterdirect the distal end of the guidewire in a deflected position throughthe lateral port 34 when the guidewire engages the second surface 33upon subsequent distal advancement of the guidewire. For example, thecatheter 30 may be advanced over the proximal end of a wire so that thewire passes over the distal surface 31 of the deflecting mechanism 36,and back into the main lumen of the catheter 30. In general, thecatheter 30 is advanced distally in an over the wire manner relative tothe guidewire when the distal tip of the guidewire is believed to lierelatively distal to a vascular occlusion within a blood vessel wall.The catheter 30 may be advanced over the wire so the distal tip of thecatheter enters the subintimal space and approaches the distal end ofthe guidewire. By retracting the distal end of the wire within the lumenof catheter 30 so that its distal tip is proximal to the deflectingmechanism 36, subsequent distal advancement of the wire thereafter willengage the proximal surface 33 of the deflecting mechanism and cause thewire to be deflected laterally through lateral port 34.

44. Several examples of active deflecting mechanisms for redirecting aguidewire are illustrated in FIGS. 5-6. A catheter 40 may be formed witha distal port 42 and a lateral port 44 as shown in FIG. 5. Rather than apassive deflecting mechanism, the catheter 40 may include an axiallytranslatable cannula 46 having a resilient, pre-formed distal tip whichmay be advanced through port 44 as shown with broken lines. The cannula46 may include a lumen which provides a guide path for the wire (notshown) when the cannula is placed in a deflected or non-deflectedposition. Meanwhile, the catheter 50 illustrated in FIG. 6 is similar tothe catheter 40 in FIG. 5, except that no lateral port is provided.Instead, a cannula 52 having a preformed distal end may be advanced andretracted out of a distal port 54 of the catheter 50 so that its distalend can assume a laterally deflected shape as shown with broken lines.It will be appreciated that these embodiments are intended to beexemplary only, and a wide variety of other passive and activedeflecting mechanisms may be provided on deflecting catheters for use inaccordance with the concepts of the present invention.

45. Referring now to FIGS. 7-10, an exemplary deflecting catheter 100formed in accordance with the principles of the present invention isdescribed in detail according to relative catheter sections. As showngenerally in FIG. 7, the deflecting catheter 100 comprises a catheterbody 102 having a distal end 104 and a proximal end 106. Catheter body102 includes a single lumen 108, as shown in FIGS. 8-10, and adeflecting housing 110 secured to the distal end 104 thereof. Anactuator hub 1 12 may be secured to the proximal end 106 of catheterbody 102, and an axially translatable cannula may be disposed withinlumen 108. The cannula 114 may be formed with a sharpened tip 116,typically formed from a metal, hard plastic, composite, or the like,optimally being radiopaque. Alternatively or additionally, it may bedesirable to provide at least one separate radiopaque marker or thecannula at or near its distal end to facilitate visualization underfluoroscopic imaging. A distal length 118 of the cannula 114 can bepre-formed with a curved shaped as shown in FIGS. 7 and 9. Arotationally specific radiopaque marker 120 may be mounted near thedistal end of catheter body 102. As illustrated, the marker has agenerally U-shaped or otherwise directional configuration so that therotational position of the distal end of the catheter body 102 will beapparent when the marker is observed in a two-dimensional fluoroscopicimage.

46. The catheter 100 provides lateral deflection to the distal tip ofthe cannula 114 which extends beyond the catheter body 102 through alateral opening 122 in the deflector housing 110 as shown in FIGS. 7-9.The deflector housing 110 also includes a distal port 124 to permitintroduction of the catheter 100 over the proximal end of a guidewire GWas illustrated in FIG. 8 with broken lines. The guidewire GW passesthrough the distal port 124, and into the distal end of the cannula 114,and may travel through a lumen of cannula all the way to the proximalend of the catheter 100. The distal length 118 of cannula 114 may bestraightened and deflected by axially retracting and advancing thecannula between the configuration shown in FIGS. 8 and FIG. 9,respectively. The cannula 114 may be formed with an appropriate diameteror cross-section to permit its passage through the layers of bloodvessel wall and may range from approximately 1F to 4F. The cannula 114may be formed of from a wide range of biocompatible materials such aspolyimide, PEEK or nitinol. Similarly, the guidewire GW should also havedimensions that allow its travel through the relatively thin layers of ablood vessel wall, and may range from approximately 0.010 in. to 0.038in. The GW may be a conventional intravascular guidewire and may beformed of a variety of materials including stainless steel and nitinol.The distal tip of the cannula 114 may include a tissue penetratingelement 116 to assist the cannula in re-entering the lumen of a bloodvessel from within the wall region. The cannula 114 should providesufficient stiffness in order to transmit enough force to penetrate theinner blood vessel wall but not enough so as traverse the outer vesselwall to regions outside of the blood vessel. The tissue penetratingelement 116 may be formed of gold-plated stainless steel, platinum, orplatinum iridium alloy or other radiopaque materials.

47.FIG. 10 provides an illustration of an actuator hub 112 comprising apair of coaxial, telescoping tubes 130 and 132. The outer telescopingtube 132 may be connected to a proximal end of cannula 114, typically byan adhesive 134 or any other connective material. A proximal fitting 136is further attached to the proximal end of the outer telescoping tube132 so that the assembly of the cannula 114, the tube 132, and thefitting 136 may move together as a unit through the hemostatic fitting140 at the proximal end of the hub 112. The hub 112 may further includea rotational fitting 142 which permits the catheter body 102 to berotated relative to the hub body. The cannula 114 and catheter body 102may be rotationally coupled or “keyed” together to limit or preventrelative rotation, typically by keying within the hub and/or near thedistal end, so that rotation of the catheter body causes a like rotationof the cannula as the catheter is rotationally positioned within a bloodvessel. A side branch 148 may be provided on hub 112 to permit perfusionand/or infusion through the lumen 108 of catheter 102.

48. Keying at the proximal end of the catheter 100 can be achieved in avariety of ways. For example, the telescoping tubes 130 and 132 can beprovided with asymmetric, mating peripheral geometries, such as ovalcross-sections shown in FIG. 11A or triangular cross-sections shown inFIG. 11B. Keying at the distal end can also be achieved in a number ofways, such as providing-the catheter body 102 with an asymmetric lumen108′ and the cannula 114′ with a mating cross-section, e.g. a D-shapedcross-section as illustrated in FIG. 12. The ability to limit relativerotation of the cannula 114 within the catheter body 102 is advantageoussince it may ensure that the curved distal length 118 is properlyoriented (usually directed radially outwardly) when the tip 116 emergesthrough the opening 122. In use, the catheter 100 may be advanced overguidewire GW while the cannula 114 is retracted as shown in FIG. 8. Oncethe catheter is properly positioned, the cannula 114 may be distallyadvanced as shown in FIGS. 7 and 9. Distal advancement may be achievedby forwardly advancing the sleeve 132 in the hub 112 relative to theremainder of the hub so that the cannulas move forwardly within thelumen 108 of the catheter body 102. Prior to advancing the cannula, theport 122 may be properly positioned so that it is directed toward theblood vessel lumen by rotating catheter body 102, typically using therotational hub 142. Conveniently, the physician may observe the marker120 so that the lateral port 122 can be directed in the proper radiallyinward direction. After the cannula is advanced into the blood vessel,the guidewire GW may then be advanced distally into the lumen, thecannula 114 may be withdrawn proximally, and the entire catheterassembly may be then withdrawn from over the guidewire leaving theguidewire in place for introduction of other interventional and/ordiagnostic catheters.

49. The deflection of a guidewire and/or cannula from within a vascularwall into the blood vessel lumen may be achieved by numerous deflectingmechanisms as described herein. For example, as shown in FIGS. 13A-C, aguidewire deflection system may be formed with a deflection noseconeassembly attached to the distal end of a catheter body. The noseconeassembly may be approximately 0.25 in. in length, and may of course varyin shape and dimensions according to particular applications. Thecatheter body (not shown) may further include a proximal portion, alongitudinal axis, and at least one lumen extending along at least adistal end portion thereof. As shown in FIG. 13A, a nosecone 200 may beformed with a distal opening 204, a relatively proximal and spaced apartlateral opening 206, and an inclined surface 208 adjacent to the lateralopening. The distal opening 204 of the nosecone 200 may have asubstantially circular cross-section ranging from approximately 2F to6F. The lateral opening 206 may be configured with an oblong orelliptical cross-section with a relatively lateral diameter of about0.014-0.050 in., and a relatively longitudinal diameter of about0.050-0.200 in. as shown in FIG. 13B. The distal opening 204 and thelateral opening 206 may be spaced apart approximately 2-5 mm, andpreferably about 3 mm, or at other various distances along the nosecone200, and may be both in communication with the catheter body lumen asshown in FIG. 13C. The lateral opening 206 and adjacent inclined surface208 may receive a cannula passing therethrough from the catheter bodylumen. In particular, the cannula (not shown) may have an externalcannula surface that is configured and sized for slidable movementthrough the lateral opening 206 specifically. The cannula may be formedwith at least one passageway extending through at least a distal portionthereof. The distal end of the cannula may be configured to communicatewith the inclined surface 208 adjacent to the lateral opening so as todeflect the cannula away from the longitudinal axis of the catheter bodywhen the cannula is advanced in a relatively distal direction.Additionally, the distal portion of the cannula may have a pre-formedshape resilient curve, and may be slidably positioned within the lumenof the catheter body. The distal cannula portion may have a relativelyaxially aligned configuration with the lumen when the cannula ispositioned within the catheter body, and may have a relatively curvedconfiguration with the lumen when the cannula travels along the inclinedsurface 208 and through the lateral opening 206 of the catheter bodywhen the cannula is distally advanced through the lumen within thecatheter body. The preformed shape resilient curve at the distal portionof the cannula may extend over an arc in the range from approximately 15to 135 degrees, and may have a radius in the range from approximately 1mm to 20 mm. The cannula may also include a self-penetrating distal endthat includes a sharpened distal tip. Moreover, the cannula may includea radiopaque or orientation marker substantially near its distal end oralong any portion thereof.

50. The guidewire deflection system may farther include a guidewireconfigured to pass through a passageway formed in the cannula. Theguidewire (not shown) may be formed with an external guidewire surfacethat is configured or sized for slidable movement through the distalopening 204 of the nosecone 200, and may range from approximately0.010-0.038 in. When the guidewire is initially placed within the layersof blood vessel wall along a selected dissection plane, the distalopening 204 of the nosecone 200 may receive the proximal end of theguidewire to permit its passage therethrough and along a longitudinallumen formed within a cannula in the attached catheter body. Thenosecone 200 may be tapered and formed with a substantially circular orelliptical cross-section, or may even have a wedge shaped cross-sectionor any other configuration that may facilitate passage in between thevessel layers along the selected dissection plane. Moreover, a hub (notshown) may be rotationally secured to the proximal end of the catheterbody to controllably rotate the cannula and the catheter body (seegenerally FIG. 10). The hub may further include a controller connectedto the cannula for controlling the slidable movement of the cannulawithin the catheter body (see generally FIG. 7). After the location andorientation of the distal tip of the guidewire is ascertained, theguidewire may be deflected into the blood vessel lumen by withdrawingthe cannula and guidewire in a relatively proximal direction so at leastthe distal tip of the cannula is proximal to the lateral port 206 andthe inclined surface 208. The cannula may be then advanced in arelatively distal direction so the tip of the cannula, which may berelatively sharpened, engages the inclined surface 208 adjacent to thelateral port 206. The guidewire may be advanced distally thereafter, andrelatively lateral deflection of the guidewire is thus achieved by thedeflection nosecone assembly. Additionally, the guidewire, cannula, orcatheter body may also include means for imaging tissue surrounding thewire. The distal end of the catheter body may include a fluoroscopicallyvisible marker substantially near its distal end to permit visualdetermination of the rotational orientation of the nosecone 200. Thenosecone 200 may likewise have a variety of fluoroscopic markers.

51.FIGS. 14A-B provide additional illustrations of an intravascularcatheter that includes a guidewire deflection assembly 210. The cathetermay be formed with a pair of relatively inner and outer shafts 212 and214 that are coaxially positioned with respect to each other. A noseconeportion 215 may be connected to the-distal end 216 of the outer cathetershaft 214 by known techniques in the art. Additionally, a cannula 220may be positioned within the catheter that is formed with a guidewirepassageway and an external cannula surface. The cannula 220 may beconnected to the inner shaft 212, and may be slidably positioned withinat least a portion of the longitudinal lumen 224 of the outer cathetershaft 214. The cannula 220 may not necessarily extend within the entirelength of the catheter, and may be located external to the catheteralong some relatively proximal portion. As shown in FIG. 14B, the distalend of the inner shaft 212 may come in contact with the proximal end ofthe nosecone 215 when advanced distally so as to controllably limit theextended length of the cannula 220. The external surface of the cannula220 may be configured for selective passage of the cannula through afirst or lateral port 226 but not through a second or distal port 228formed in the nosecone 215. A guidewire 230 formed with an externalsurface may be thus configured for passage through the distal port 228too, and may be slidably positioned within at least a portion of thecannula passageway. When the cannula 220 is positioned relativelycoaxial within the catheter, the guidewire 230 within the cannula may bedirected to enter or to exit the catheter through the distal port 228.The first port 226 in the nosecone 215 may have a first transversecross-sectional area, and may be in communication with a longitudinallumen 224 that is defined by the inner walls of the outer shaft 214. Thesecond port 228 may also be in communication with the longitudinal lumen224, wherein the second port is formed with a second transversecross-sectional area. The first cross-sectional area may be relativelylarger or smaller than the second cross-sectional area, and arepreferably formed with different dimensions or configurations soselective passage of the cannula 220 may be achieved.

52. A variety of imaging and orientation markers may be also positionedalong various portions of the guidewire 230, cannula 220 and/or catheterbody. In particular, the nosecone 215 may include a radiopaque marker orimaging componentry that provides directional orientation of the distalportion of the catheter or the relative direction in which the lateralport 226 is facing. The nosecone 215 may include ports of various sizes,and may define a first port 226 as a substantially elliptical orificeand the second port 228 as a substantially circular orifice. Theimmediate area of nosecone 215 surrounding the first port 226 may definean inclined surface 232 for receiving a distal cannula tip section 234that leads to the first port.

53. Additional guidewire deflecting mechanisms provided in accordancewith the invention are shown in FIGS. 15-20. A flapper assembly 240, asshown in FIGS. 15A-E, may be positioned at the distal portion of acatheter to controllably deflect a guidewire 242. The flapper assembly240 may be formed at the distal end of a catheter shaft to provide aredirectable intravascular guidewire catheter. The catheter shaft (notshown) may have a distal end, a proximal end, a longitudinal axis, andat least one lumen extending along at least a portion of catheter shaftand the longitudinal axis of the catheter shaft. The flapper assembly240 may have a distal end port 244, a lateral port 246, and a flappervalve or mechanism 248 with a deflectable extension 250. The deflectableextension 250 may include a biased inclined surface which may havemultiple curved sections. Additionally, as shown in FIGS. 15A-B, thedeflectable extension 250 may have a first position or configurationthat directs a guidewire tip 254 through the distal end port 244 whenthe guidewire tip is positioned relatively distal to the deflectableextension 250. The deflectable extension 250 may also have a secondposition that directs the guidewire tip 254 through the lateral port 246when the tip is positioned relatively proximal to the deflectableextension 250, and advanced thereafter in a relatively distal directionas shown in FIGS. 15C-D. The flapper valve 248 may be also formed with arelatively distal collar 256 that is positioned substantially adjacentto the distal end port 244. The distal collar 256 may be formed with alongitudinal length defined by the distance between the lateral port 246and the distal port 244. At least a portion of the flapper assembly 240,including the collar portion 256, may be formed of a fluoroscopic orradiopaque material to provide an orientation marker for directionalplacement of the guidewire 242.

54. In another variation of the invention, as shown in FIG. 16A, theflapper mechanism 260 may be formed relatively externally or relativelyouter to the catheter body 262. The collar portion 266 of the flappermechanism 260 may be positioned on the outer surface of the catheterbody 262 along a relatively distal portion or along any other section ofthe same. Furthermore, the deflectable extension 270 may be integrallyformed or connected to the collar 266, and may extend through arelatively distal portion of the lateral opening 264 into the interiorlumen of the catheter body 262. Although the guidewire deflectors shownin the preceding illustrations have been depicted as separatecomponents, they may be of course integrally formed from a single pieceof suitable material. In addition, as shown in FIG. 16B, a guidewire maybe inserted into the interior lumen of the catheter body 262 through anopening 263 that may be formed relatively proximal to the flappermechanism 260. The guidewire may be still positioned in at least arelatively distal portion of the interior catheter lumen. A relativelyrigid or stiff member 269, which may be formed of stainless steel, maythus occupy a substantial proximal length of the catheter body lumen, toprovide improved torque transmission.

55.FIGS. 17A-D illustrates the distal section of a redirectableguidewire catheter. The redirectable guidewire catheter may comprise acatheter shaft 280 formed with a first lumen 282 and a second lumen 284each extending along the catheter shaft respectively to a first distalopening 286 and a second distal opening 288. The catheter may include anactuator wire 290 slidably positioned with the first lumen 282 of thecatheter shaft 280. The actuator wire 290 may be formed with a preformeddistal end 292 to provide an actuated position that substantiallyextends or is biased towards the second distal opening 288 when advancedrelatively distal through the first distal opening 286. The seconddistal opening 288 may be thus obstructed or at least covered in partwhich will tend to direct a guidewire 285 passing through the secondlumen 284 and distal opening 288 away from the longitudinal axis of thecatheter shaft 280. The guidewire 285 may be slidably positioned withinthe second lumen 284 of the catheter shaft 280, and may be deflectedwhen advanced relatively distal through the second distal opening 288and when the actuator wire 290 is placed in its actuated position. Asshown in FIG. 17A, the actuator wire 290 may extend through the firstdistal opening 286 of the first lumen 282 and may still remain within aninterior distal nosecone portion 295 of the catheter. The distal mosttip 294 of the actuator wire 290 may be formed with a flattened portionthat rests on a relatively level surface within the nosecone portion.Alternatively, the actuator wire 290 may be configured to extend outsideof or beyond the outer surface of the catheter body or nosecone portion295 (not shown). The first distal opening 286 and/or the second opening288 may be formed at the distal most end portions of the catheter shaft280 or at some point relatively proximal thereof. The first and secondlumens 282 and 284, which lead to their respective distal openings 286and 288, may be formed with a variety of cross-sectional configurationsand positions relative to one another. For example, as shown in FIG.17B, the actuator wire lumen 282 may be formed with a crescent orarc-shaped configuration to guide an actuator wire 290 therethrough. Theguidewire lumen 284 may be formed with conventional circularcross-section and positioned side-by-side relative to the actuator wirelumen 282. The actuator wire lumen 282 may have an inner radius of about0.017 in., and an outer radius of about 0.014 in. The guidewire lumen284 may be also formed with a diameter of about 0.018 in. The outerdiameter of the catheter shaft 280 may be about 0.036 in. Thesedimensions may be of course varied according to particular applications.At least a distal portion of the actuator wire 290 may be thus formed ofa half-cylinder hypotube, as shown in FIG. 17C, for slidable movementwithin the actuator wire lumen 282. This configuration may further guideor direct a guidewire 285 extending from the adjacent lumen 284. Theactuator wire 290 may of course have a proximal section formed with anyother type of cross-section, and may include only a distal section thatis formed with an arc-shaped region to controllably deflect theguidewire 285 in a predetermined direction.

56.FIGS. 18A-C illustrates the distal section of a nosecone assembly 300formed at the distal end of a redirectable guidewire catheter. Thecatheter may be configured for crossing a substantially occluded bloodvessel, and may include a catheter shaft formed with a distal portionand a longitudinal axis, and wherein the catheter shaft has a firstlumen and a second lumen each extending along the catheter shaft (seegenerally FIG. 17B). The first and the second lumen may be alsoconfigured in a relatively side-by-side configuration along the cathetershaft. As shown in FIG. 18A, a nosecone 300 may be formed at the distalportion of the catheter shaft (not shown), and may include a singledistal orifice 302 and an interior region 304. The interior region 304of the nosecone 302 may be formed with a tapered surface 306 that isshaped to contact an actuator wire 308. The actuator wire 308 may beslidably positioned with the first lumen of the catheter shaft. Thedistal tip of the actuator wire 308 may be redirected substantially awayfrom the longitudinal axis of the catheter shaft when advancedrelatively distal along the tapered surface 306 of the nosecone 300 andthrough the nosecone orifice 302. The actuator wire 308 may remainwithin the interior region 304 of the nosecone section 300, or it mayextend further away from or beyond the catheter shaft to penetratetissue in adjoining area. A guidewire 310 may be also slidablypositioned within the second lumen of the catheter shaft. The guidewire310 may be initially positioned within the selected dissection planewithin a blood vessel wall, and may support positioning of the catheterin an over the wire manner. When the catheter is passed over theproximal portion of the guidewire and distally advanced, as shown inFIG. 18B, the guidewire 310 may travel in a relatively linear fashionalong the longitudinal axis of the catheter shaft. However, when thedistal end of the guidewire 310 is retracted into the nosecone section302, and the actuator wire 308 extended distally, subsequent advancementof the guidewire will result in its deflection and movement away fromthe catheter shaft in an askew manner. As shown in FIG. 18C, theguidewire 310 is deflected away from the longitudinal axis of thecatheter shaft by contacting the redirected actuator wire 308 when theguidewire is advanced relatively distal through the distal orifice 302.The orifice 302 may be formed at the distal most end of the cathetershaft or along any relatively proximal portion thereof. The cathetershaft and the nosecone 302 may be integrally formed or separately formedand joined together by conventional techniques.

57.FIG. 19 illustrates another embodiment of the invention that providesan intravascular catheter for selectively deflecting a guidewire. Thecatheter body 320 may be formed with a longitudinal lumen that includesa support tube 322 slidably and rotatably positioned within thelongitudinal lumen of the catheter body. The support tube 322 may have adistal tube end and a tube port 324, and may also define a conduit thatis in fluid communication with the tube port. The distal tube end may bealso formed with a cut-out portion 326. The catheter may also include acannula 328 having a distal cannula end, a cannula port 330 formed atits distal end, and at least one passageway extending through at least adistal end portion thereof in fluid communication with the cannula port.The distal portion of the cannula may have a preformed shape resilientcurve, and may be slidably positioned within the conduit of the supporttube 322. The support tube 322 may have a longitudinal axis so that thedistal portion of the cannula is relatively aligned with respect to thelongitudinal axis of the support tube when the cannula 328 is positionedwithin the support tube, and is relatively askew with respect to thelongitudinal axis of the support tube when the distal cannula endextends beyond the distal end of the catheter body 320. A guidewire (notshown) may be positioned within at least a portion of the cannulapassageway. When the support tube 322 and the cannula 328 are placed ina retracted position within the catheter body 320, the distal opening ofthe cannula 328 within the catheter may pass over the guidewire. Thecatheter body 320 may be moved relatively proximally so the support tube322 extends beyond the catheter body to expose the cut-out portion 326of the support tube. The cannula 328 within the support tube 322 may bethereafter advanced distally in order for the preformed distal cannulaportion to deflect away from the longitudinal axis of the catheter body320. The distal tip of the guidewire may be thus deflected insubstantially the same direction as the distal portion of the cannulawhen advanced in a relatively distal direction within the cannula 328.The proximal tube end of the support tube may be also connected to arotating assembly (not shown) to rotate the support tube relative to thecatheter body. The cut-out portion 326 of the support tube 322 may bealigned in a specific manner which guides the general direction in whichthe distal cannula portion is pointed and extended outside of thecatheter.

58. Another intravascular catheter provided in accordance with theinvention is further shown in FIG. 20. The catheter may also include acatheter body 340 formed with a distal end, a catheter port 342, alongitudinal axis, and a longitudinal lumen formed along at least adistal portion of the catheter body in fluid communication with thecatheter port. A cannula 348 with a distal cannula end 344 may beslidably positioned within the longitudinal lumen of the catheter body340. At least one passageway may be formed in the cannula 348 which mayprovide for slidable movement of a guidewire. The passageway may be influid communication with a cannula port formed at the distal end 344 ofthe cannula. The distal end 344 of the cannula may further include asupport tube section 350. The support tube 350 may be formed with adistal tube end section 352, a proximal tube end section 354, and abackbone 356 connecting the distal and the proximal tube end sections.The backbone 356 of the support tube 350 may include a plurality ofcut-out rib sections. The removed portions of the support tube 350 mayprovide reduced compression and increased flexibility of the supporttube, and may support more responsive deflecting movement of the distalcannula end 344. The support tube 350 may be also preformed with apredetermined shape to deflect the distal cannula end 344 away from thelongitudinal axis of the catheter body 340 when the distal cannula endis extended proximally past the distal end of the catheter body.Alternatively or additionally, the distal cannula end 344 may bepreformed with a predetermined shape that deflects away from thelongitudinal axis of the catheter body 340 end when extended past thedistal end of the catheter body. The cannula 348 may be slidably movablewithin the longitudinal lumen of the catheter body 340. As with othercannulas described herein, the proximal end of the cannula may beconnected to a hub assembly that provides or supports rotational orlongitudinal movement of the cannula in either a relatively distal orproximal movement relative to the catheter body.

59. While all aspects of the present invention have been described withreference to the aforementioned applications, this description ofvarious embodiments and methods shall not be construed in a limitingsense. The aforementioned is presented for purposes of illustration andcomplete description that are consistent with all applicable standards.It shall be understood that all aspects of the invention are not limitedto the specific depictions, configurations or relative proportions setforth herein which depend upon a variety of conditions and variables.The specification is not intended to be exhaustive or to limit theinvention to the precise forms disclosed herein. Various modificationsand insubstantial changes in form and detail of the particularembodiments of the disclosed invention, as well as other variations ofthe invention, will be apparent to a person skilled in the art uponreference to the present disclosure. It is therefore contemplated thatthe appended claims shall cover any such modifications, variations orequivalents as to the described embodiments as falling within the truespirit and scope of the invention.

What is claimed is:
 1. A guidewire deflection system comprising: acatheter body having a proximal end, a distal end, a longitudinal axis,and at least one lumen extending along the catheter body; a noseconeformed at the distal end of the catheter body having a distal opening incommunication with the catheter body lumen, a lateral opening spacedrelatively proximal to the distal opening that is in communication withthe catheter body lumen, and an inclined surface formed proximallyadjacent to the lateral opening; and a cannula having a proximal end, adistal end, and at least one passageway extending through at least adistal portion of the cannula, wherein the distal end of the cannula isconfigured to deflect away from the longitudinal axis of the catheterbody when the distal end thereof engages the inclined surface adjacentto the lateral opening.
 2. A guidewire deflection system as recited inclaim 1 , wherein the distal portion of the cannula has a pre-formedshape resilient curve and is slidably positioned within the lumen of thecatheter body, and wherein the distal portion has a relatively axiallyaligned configuration with the lumen when the cannula is positionedwithin the catheter body, and a relatively curved configuration with thelumen when the cannula travels along the inclined surface and throughthe lateral opening of the catheter body when the cannula is distallyadvanced through the lumen within the catheter body.
 3. A guidewiredeflection system as in claim 2 , wherein the pre-formed shape resilientcurve at the distal portion of the cannula extends over an arc in therange from 15 to 135 degrees.
 4. A guidewire deflection system as ineither claim 2 , wherein the pre-formed shape resilient curve has aradius in the range from 1 mm to 20 mm.
 5. A guidewire deflection systemas recited in claim 1 , wherein the cannula is configured for slidablemovement through the lateral opening.
 6. A guidewire deflection systemas recited in claim 1 , further comprising a guidewire configured topass through the passageway of the cannula.
 7. A guidewire deflectionsystem as recited in claim 6 , wherein the guidewire is configured forslidable movement through the distal opening of the nosecone.
 8. Aguidewire deflection system as recited in claim 6 , wherein theguidewire has a sharpened distal tip.
 9. A guidewire deflection systemas in claim 6 , wherein the guidewire comprises means for imaging tissuesurrounding the wire.
 10. A guidewire deflection system as in claim 1 ,wherein the cannula is formed with a self-penetrating distal end.
 11. Aguidewire deflection system as recited in claim 10 , wherein theself-penetrating distal end includes a sharpened distal tip.
 12. Aguidewire deflection system as recited in claim 1 , wherein the cannulaincludes a radiopaque marker substantially near its distal end.
 13. Aguidewire deflection system as recited in claim 1 , wherein the distalend of the cannula includes a radiopaque marker.
 14. A guidewiredeflection system as recited in claim 1 , wherein the distal end of thecatheter body includes a fluoroscopically visible marker substantiallynear its distal end to permit visual determination of the rotationalorientation of the nosecone.
 15. A guidewire deflection system as inclaim 1 , wherein the nosecone is formed with a substantially circularcross-section.
 16. A guidewire deflection system as in claim 1 , whereinthe nosecone is formed with a wedge shaped cross-section.
 17. Aguidewire deflection system as in claim 1 , wherein the nosecone isformed with a substantially elliptical cross-section.
 18. A guidewiredeflection system as in claim 1 , further comprising a hub rotationallysecured to the proximal end of the catheter body to controllably rotatethe cannula and the catheter body.
 19. A guidewire deflection system asin claim 18 , wherein the hub includes a cannula controller connected tothe cannula for controlling the slidable movement of the cannula withinthe catheter body.
 20. An intravascular catheter comprising: a cathetershaft having a distal end and a longitudinal lumen; a noseconepositioned at the distal end of the catheter shaft having a first portin communication with the longitudinal lumen formed with a firsttransverse cross-sectional area, and a second port in communication withthe longitudinal lumen formed with a second transverse cross-sectionalarea relatively smaller than the first transverse cross-sectional area;a cannula having a passageway that is slidably positioned within atleast a portion of the longitudinal lumen of the catheter shaft, and isconfigured for passage through the first port but not through the secondport of the nosecone; and a guidewire that is slidably disposed withinat least part of the cannula passageway and is configured for passagethrough the second port.
 21. An intravascular catheter as recited inclaim 20 , wherein the nosecone includes an imaging component thatprovides directional orientation.
 22. An intravascular catheter asrecited in claim 20 , wherein the nosecone includes a radiopaque marker.23. An intravascular catheter as recited in claim 20 , wherein thenosecone defines the first port as a substantially circular orifice andthe second port as a substantially elliptical orifice.
 24. Anintravascular catheter as recited in claim 23 , wherein the noseconefurther defines an inclined surface leading to the second port.
 25. Anintravascular catheter as recited in claim 24 , wherein the noseconedefines the first port and the second port, further defines an inclinedsurface.
 26. A redirectable intravascular guidewire catheter comprising:a catheter shaft having a distal end, a proximal end, a longitudinalaxis, and at least one lumen extending along at least a portion ofcatheter shaft; and a guidewire deflector formed at the distal end ofthe catheter shaft having a distal end port, a lateral port, and aflapper assembly with a deflectable extension having a first positionthat directs a guidewire tip through the distal end port when theguidewire tip is positioned relatively distal to the deflectableextension, and a second position that directs the guidewire tip throughthe lateral port when the tip is positioned relatively proximal to thedeflectable extension and advanced thereafter in a relatively distaldirection.
 27. A redirectable intravascular guidewire catheter asrecited in claim 26 further comprising a guidewire that is slidablypositioned within the lumen of the catheter shaft.
 28. A redirectableintravascular guidewire catheter as recited in claim 26 , wherein atleast a portion of the flapper assembly is formed of a radiopaquematerial to provide an orientation marker for directional placement of aguidewire.
 29. A redirectable intravascular guidewire catheter asrecited in claim 26 , wherein the flapper assembly is formed with arelatively distal collar that is positioned substantially adjacent tothe distal end port.
 30. A redirectable intravascular guidewire catheteras recited in claim 26 , wherein the distal collar is includesradiopaque material.
 31. A redirectable intravascular guidewire catheteras recited in claim 26 , wherein the distal end of the catheter shaft isformed with an exterior surface, and wherein the relatively distalcollar of the flapper valve is positioned on the exterior surface of thedistal end of the catheter shaft.
 32. A redirectable intravascularguidewire catheter as recited in claim 26 , wherein the guidewiredeflector and the catheter shaft are integrally formed.
 33. Aredirectable intravascular guidewire catheter as recited in claim 26 ,wherein the proximal end of the catheter shaft includes a stainlesssteel wire, and wherein the catheter shaft is formed with an openingrelatively distal to the wire for passage of a guidewire.
 34. Aredirectable guidewire catheter comprising: a catheter shaft formed witha distal end, and having a first lumen and a second lumen each extendingalong the catheter shaft respectively to a first distal opening and asecond distal opening; an actuator wire slidably positioned within thefirst lumen of the catheter shaft, wherein the actuator wire is formedwith a preformed distal end to provide an actuated position that isbiased towards the second distal opening when advanced relatively distalthrough the first distal opening; and a guidewire slidably positionedwithin the second lumen of the catheter shaft that may be deflected whenadvanced relatively distal through the second distal opening and whenthe actuator wire is placed in its actuated position.
 35. A redirectableguidewire catheter as recited in claim 34 , wherein at least a portionof the actuator wire is formed of a half-cylinder hypotube.
 36. Aredirectable guidewire catheter as recited in claim 34 , wherein thepreformed distal end of the actuator wire is formed with a arc-shapedcross-section.
 37. A redirectable guidewire catheter as recited in claim34 , wherein the actuator wire extends beyond the outer surface of thecatheter shaft.
 38. A redirectable guidewire catheter comprising: acatheter shaft formed with a distal portion and a longitudinal axis, andwherein the catheter shaft has a first lumen and a second lumen eachextending within the distal portion of the catheter shaft; a noseconeformed at the distal portion of the catheter shaft, wherein the noseconeincludes a distal orifice and an interior region, and wherein theinterior region of the nosecone is formed with a tapered surface and isin communication with the first and second lumens; an actuator wireformed with a distal tip that is slidably positioned within the firstlumen of the catheter shaft, wherein the distal tip of the actuator wireis redirected substantially away from the longitudinal axis of thecatheter shaft when advanced relatively distal along the tapered surfaceof the nosecone and through the nosecone orifice; and a guidewireslidably positioned within the second lumen of the catheter shaft thatmay be deflected away from the longitudinal axis of the catheter shaftby contacting the redirected actuator wire when the guidewire isadvanced relatively distal through the distal orifice.
 39. Aredirectable guidewire catheter as recited in claim 38 , wherein thecatheter shaft has a distal most end, and wherein the orifice is formedat the distal most end of the catheter shaft.
 40. A redirectableguidewire catheter as recited in claim 39 , wherein the catheter shaftand the nosecone are integrally formed.
 41. A redirectable guidewirecatheter as recited in claim 38 , wherein the first and the second lumenare arranged in a side-by-side configuration.
 42. An intravascularcatheter for selectively deflecting a guidewire comprising: a catheterbody formed with a distal end and a longitudinal lumen formed along atleast a portion of the catheter body; a support tube having a distaltube end, a proximal tube end, a tube port formed at the distal tubeend, and a conduit formed within the support tube in communication withthe tube port, wherein the distal tube end is formed with a cut-outportion, and wherein the support tube is slidably and rotatablypositioned within the longitudinal lumen of the catheter body; and acannula having a distal cannula end, a cannula port formed at the distalcannula end, and at least one passageway extending through at least adistal end portion of the cannula that is in communication with thecannula port, wherein the distal portion of the cannula has a pre-formedshape resilient curve, and wherein the cannula is slidably positionedwithin the conduit of the support tube.
 43. An intravascular catheter asrecited in claim 42 , wherein the support tube has a longitudinal axis,and wherein the distal portion of the cannula is relatively aligned withrespect to the longitudinal axis of the support tube when the cannula ispositioned within the support tube, and is relatively askew with respectto the longitudinal axis of the support tube when the distal cannula endextends beyond the distal end of the catheter body.
 44. An intravascularcatheter as recited in claim 43 , further comprising a guidewire with adistal tip positioned within at least a portion of the cannulapassageway, wherein the distal tip of the guidewire is deflected insubstantially the same direction as the distal portion of the cannula.45. An intravascular catheter as recited in claim 43 , wherein theproximal tube end of the support tube is connected to a rotatingassembly to rotate the support tube relative to the catheter body. 46.An intravascular catheter for selectively deflecting a guidewirecomprising: a catheter body formed with a distal end, a catheter portformed at the distal end of the catheter body, a longitudinal axis, anda longitudinal lumen extending within at least a distal portion of thecatheter body in communication with the catheter port; a cannula havinga distal cannula end, a cannula port formed at the distal cannula end,and at least one passageway formed within at least a distal portion ofthe cannula in communication with the cannula port, wherein the cannulais slidably positioned within the longitudinal lumen of the catheterbody; and a support tube connected to the distal cannula end, whereinthe support tube is formed with a distal tube end section, a proximaltube end section, and a backbone connecting the distal and the proximaltube end sections.
 47. An intravascular catheter as recited in claim 46, wherein the support tube is preformed with a predetermined shape todeflect the distal cannula end away from the longitudinal axis of thecatheter body when the distal cannula end is extended past the distalend of the catheter body.
 48. An intravascular catheter as recited inclaim 46 , wherein the distal cannula end is preformed with apredetermined shape that deflects away from the longitudinal axis of thedistal cannula end when extended past the distal end of the catheterbody.
 49. An intravascular catheter as recited in claim 46 , wherein thecannula is slidably movable within the longitudinal lumen of thecatheter body.
 50. An intravascular catheter as recited in claim 46 ,wherein the backbone of the support tube includes a plurality of cut-outrib sections.
 51. A redirectable intravascular guidewire cathetercomprising: a catheter shaft having a distal end, a proximal end, alongitudinal axis, a first port formed at the distal end of the shaft, asecond port spaced relatively proximal to the distal end of the shaft,and at least one lumen extending along at least a portion of thelongitudinal axis of the catheter shaft in communication with the firstand second ports; and a guidewire deflector formed within a distalextremity of the catheter shaft having a first surface that directs anend portion of a guidewire between the catheter shaft lumen and thefirst port, and a second surface that directs the end portion of theguidewire between the catheter shaft lumen and the second port.
 52. Theredirectable intravascular guidewire catheter as recited in claim 51 ,wherein the guidewire deflector includes a flapper valve having a firstposition that provides the first surface for contact with the guidewire,and a second position that provides the second surface for contact withthe guidewire.
 53. A method for crossing a substantially occluded bloodvessel, said method comprising: selecting a guidewire with a deflectabledistal tip configured for advancement within a lumen of a blood vesselwall; creating a longitudinal dissection plane within a wall the bloodvessel by inserting the guidewire into blood vessel wall from within theblood vessel lumen at a proximal location relative to a vascularocclusion; forming a channel along the dissection plane within the bloodvessel wall by advancing the guidewire within the blood vessel wall in arelatively distal direction; and selectively deflecting the distal tipof the guidewire at a relatively distal location relative to theproximal location back into the blood vessel lumen.
 54. A method asrecited in claim 53 , wherein the blood vessel is an artery.
 55. Amethod as recited in claim 54 , wherein the artery is coronary artery.56. A method as recited in claim 53 , further comprising performing aninterventional or diagnostic procedure over the guidewire.
 57. A methodas recited in claim 53 , further comprising advancing an interventionalor diagnostic catheter over the deflected guidewire from a positionrelatively proximal to the occlusion, through the channel, and back intothe blood vessel lumen.
 58. A method as recited in claim 53 , furthercomprising imaging the occlusion and blood vessel lumen to identifytheir relative location to the guidewire.
 59. A method as recited inclaim 58 , wherein the blood vessel is an artery and the imaging stepcomprises imaging from a position in a vein adjacent to the artery. 60.A method as recited in claim 53 , wherein the distal tip of theguidewire is deflected by providing the guidewire tip with a resilientcurved end, and distally advancing the guidewire from a constraininglumen into the blood vessel lumen.